Reading config sections using Custom config classes in C# and converting them to a list

Question

I have this in my app.config file:

<Configuration>
 <configsections>
  <section name="FeaturesSection" type="SampleCatalog.FeaturesSection" />
 </configsections>
 <FeaturesSection>
   <Feature Name="CCH" US="true" EM="false" Sequence="1" />
   <Feature Name="PLT" US="true" EM="false" Sequence="1" />
   <Feature Name="PD" US="true" EM="false" Sequence="1" />
 </FeaturesSection>
<Configuration>

My code in the class goes as below:

public class FeaturesSection:ConfigurationSection
{
 public FeatureCollection Features
 {
    get{return (FeatureCollection)base["Features"};
 }
}

public class FeatureCollection:ConfigurationElementCollection
{
   public Feature this[int index]{
     get{ return (Feature)BaseGet(index);}
     set{
        if(BaseGet(index)!= null)
          BaseRemoveAt(index);
        BaseAdd(index,value);
        }
    }

    protected override ConfigurationElement CreateNewElement()
    {
      return new Feature();
    }

    protected override object GetElementKey(ConfigurationElement          element){
      return ((Feature)element);
    }
}

public class Feature: ConfigurationElement
{
   [ConfigurationProperty("Name",IsRequired=true)]
   public string Name {get; set;}

   [ConfigurationProperty("US",IsRequired=true)]
   public bool US {get; set;}

   [ConfigurationProperty("EM",IsRequired=true)]
   public bool EM {get; set;}

   [ConfigurationProperty("Sequence",IsRequired=true)]
   public string Sequence {get; set;}
  }

Now when I run this code:

var mysection = (FeaturesSection)ConfigurationManager.GetSection("FeaturesSection");

I'm getting exceptions.

An error occurred creating the configuration section handler for FeaturesSection: Could not load type 'SampleCatalog.FeaturesSection' from assembly 'System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. (C:\Users\Venkata_Poruri_Pavan\Documents\Visual Studio 2013\Projects\SampleCatalog\SampleCatalog\bin\Debug\SampleCatalog.vshost.exe.Con‌fig line 4)

Please help, kindly accept my apologies as I couldn't paste the code here.

Thanks

WHAT exceptions do you get? Please post the full and exact error message(s) you get! — marc_s
– marc_s, Commented Jan 6, 2016 at 21:51
SampleCatalog is the namespace and the FeaturesSection is the class within the namespace. — Pavan Kumar
– Pavan Kumar, Commented Jan 7, 2016 at 4:05

marc_s · Accepted Answer · 2016-01-07 07:21:42Z

1

If you have a config section type in your own assembly, you need to define that assembly in the <configSection> - try using this:

<configsections>
   <section name="FeaturesSection" 
            type="SampleCatalog.FeaturesSection, SampleCatalog" />
</configsections>

You need to specify the type= as fully-qualified class name, and then after a comma, define the assembly where that type is stored in. If you omit it (as you did in your post), .NET will check in the System.Configuration assembly - but of course, it won't find your custom class there!

Update: OK your code and config need a few little tweaks:

On the FeaturesSection, you need to add a ConfigurationProperty attribute to define under what name that collection of entries will be stored - something like this:

[ConfigurationProperty("Features")]
public class FeaturesSection : ConfigurationSection
{
    public FeatureCollection Features
    {
        get{return (FeatureCollection)base["Features"};
    }
}

On your FeatureCollection class, you need to define (with an attribute) what **type* of elements that collection will contain, and what to call the individual elements inside the collection:

[ConfigurationCollection(typeof(Feature), AddItemName = "Feature")]
public class FeatureCollection : ConfigurationElementCollection
{
    public Feature this[int index]
    {
        get { return (Feature)BaseGet(index); }
        set 
        {
            if(BaseGet(index) !=  null)
            {
                BaseRemoveAt(index);
            }

            BaseAdd(index,value);
        }
    }

    protected override ConfigurationElement CreateNewElement()
    {
        return new Feature();
    }

    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((Feature)element);
    }
}

And then your config needs to look like this:

<Configuration>
    <configSections>
        <!-- add the ASSEMBLY after the fully-qualified class name -->
        <section name="FeaturesSection" 
                 type="SampleCatalog.FeaturesSection, SampleCatalog" />
    </configSections>
    <FeaturesSection>
        <!-- this is the name defined on the FeaturesSection -->         
        <Features>
            <Feature Name="CCH" US="true" EM="false" Sequence="1" />
            <Feature Name="PLT" US="true" EM="false" Sequence="1" />
            <Feature Name="PD" US="true" EM="false" Sequence="1" />
        </Features>              
    </FeaturesSection>
<Configuration>

With this setup, you should be able to properly read out your custom config section.

edited Jan 7, 2016 at 7:21

answered Jan 7, 2016 at 5:43

marc_s

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8 Comments

Pavan Kumar Over a year ago

ConfigurationErrorException: Unrecognized Element 'Feature'

marc_s Over a year ago

@user3581188: updated my response with some code changes and a change in structure of the config section; I tested this on .NET 4.5 and it works for me

Pavan Kumar Over a year ago

Error 18 Attribute 'ConfigurationProperty' is not valid on this declaration type. It is only valid on 'property, indexer' declarations.

marc_s Over a year ago

@user3581188: where did you add the ConfgurationProperty attribute? My code as posted works (I testet it "live")

Pavan Kumar Over a year ago

[ConfigurationProperty("Features")] public class FeaturesSection : ConfigurationSection { public FeatureCollection Features { get { return (FeatureCollection) base["Features"]; } } }

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